Chapter 13 THE RESPIRATORY CHAIN AND OXIDATIVE PHOSPHORYLATION Flashcards
Respiration is coupled to the generation of the high-energy intermediate, ATP, by ____
oxidative phosphorylation
part of mitochondria that is permeable to most metabolites
Outer membrane
part of mitochondria that is selectively permeable
Inner membrane
- material inside the mitochondria,
- contains enzymes, mtDNA, mtRNA, mitochondrial ribosomes
Matrix
The outer membrane is characterized by the presence of various enzymes including ____ and ____
acyl-CoA synthetase;
glycerol phosphate acyltransferase
enzymes that are found in the intermembrane space of mitochondria
adenylyl kinase and creatine kinase
is concentrated in the inner membrane together with the enzymes of the respiratory chain, ATP synthase, and various membrane transporters
phospholipid cardiolipin
- are important components of Complexes I and II
Flavoproteins
- are found in Complexes I, II, and III
- may contain one, two, or four Fe atoms linked to inorganic sulfur atoms and/or via cysteine-SH groups to the protein
Iron-sulfur proteins (nonheme iron proteins, Fe-S)
is a large L-shaped multisubunit protein that catalyzes electron transfer from NADH to Q, coupled with the transfer of four H+ across the membrane
NADH-Q oxidoreductase or Complex I
an unusual Fe-S in which one of the Fe atoms is linked to two histidine residues rather than two cysteine residues
Rieske Fe-S
The flow of electrons through the respiratory chain generates ATP by the process of
oxidative phosphorylation
postulates that the two processes are coupled by a proton gradient across the inner mitochondrial membrane so that the proton motive force caused by the electrochemical potential difference (negative on the matrix side) drives the mechanism of ATP synthesis
chemiosmotic theory
oxidation cannot proceed via the respiratory chain without concomitant phosphorylation of ADP
because oxidation and phosphorylation are tightly coupled
inhibit electron transport via Complex I by blocking the transfer from Fe-S to Q
Barbiturates
inhibit the respiratory chain at Complex III
Antimycin A and dimercaprol
States of Respiratory Control
State 1 - Availability of ADP and substrate
State 2 - Availability of substrate only
State 3 - The capacity of the respiratory chain itself, when all substrates and components are present in saturating amounts
State 4 - Availability of ADP only
State 5 - Availability of oxygen only
inhibit Complex IV and can therefore totally arrest respiration
H2S, carbon monoxide, and cyanide
is a competitive inhibitor of Complex II
Malonate
inhibits oxidative phosphorylation by inhibiting the transporter of ADP into and ATP out of the mitochondrion
Atractyloside
completely blocks oxidation and phosphorylation by blocking the flow of protons through ATP synthase
Oligomycin
dissociate oxidation in the respiratory chain from phosphorylation
Uncouplers
(or the uncoupling protein) is a physiological uncoupler found in brown adipose tissue that functions to generate body heat, particularly for the newborn and during hibernation in anima
Thermoginin
involving transporter proteins that span the membrane are present in the membrane for exchange of anions against OH− ions and cations against H+ ions
Exchange diffusion systems
are transported into mitochondria via the carnitine system
Long-chain fatty acids
are lipophilic molecules that complex specific cations
and facilitate their transport through biologic membranes
Ionophores
augments the functions of creatine phosphate as an energy buffer by acting as a dynamic system for transfer of high-energy phosphate from mitochondria in active tissues such as heart and skeletal muscle
creatine phosphate shuttle
is found in the mitochondrial intermembrane space, catalyzing the transfer of high-energy phosphate to creatine from ATP emerging from the adenine nucleotide transporter
Isoenzyme of creatine kinase (CKm)
involves severe diminution
or absence of most oxidoreductases of the respiratory chain
fatal infantile mitochondrial myopathy and renal dysfunction
is an inherited condition due to NADH-Q oxidoreductase (Complex I) or cytochrome oxidase (Complex IV) deficiency
MELAS (mitochondrial encephalopathy, lactic acidosis, and
stroke)
- Energy from oxidation of components in the respiratory chain is couples with translocation of hydrogen ions
- hydrogen is moved from the inside to the outside of the inner mitochondrial membrane –> accumulates in the intermembranous space
Mitchell’s Chemiosmotic Theory
Inhibitors of ETC in Compex I
Amytal, Rotenone
Inhibitors of ETC in Compex II
Malonate
Inhibitors of ETC in Compex III
Anitimycin A, Dimercaprol
Inhibitors of ETC in Compex IV
Hydrogen Sulfide, Carbon Monoxide, Cyanide, Sodium Azide
Inhibitors of ETC in Compex V
Oligomycin
